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Register a new userTesting parameters in an eikonalized dynamical gluon mass model
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In the framework of a dynamical gluon mass model recently developed, we investigate the effects of two essential parameters in the description of elastic $pp$ and $bar{p}p$ data at high energies: the soft Pomeron intercept and the dynamical gluon mass. By considering relevant numerical intervals for both parameters and fits to the experimental data up to 1.8 TeV, with good statistical results, we discuss the predictions of the physical quantities at the LHC energies (7 and 14 TeV). We conclude that these quantities are sensitive to those variations and the predictions are correlated with the intervals considered for both parameters. This conclusion puts limits on the reliability of QCD inspired models predictions at the LHC energies, mainly those models with ad hoc fixed values for the mass scale and the Pomeron intercept.
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The role of low-$x$ parton dynamics in dictating the high-energy behavior of forward scattering observables at LHC energies is investigated using a QCD-based model with even-under-crossing amplitude dominance at high-energies. We explore the effects of different sets of pre- and post-LHC fine-tuned parton distributions on the forward quantities $sigma_{tot}$ and $rho$, from $pp$ and $bar{p}p$ scattering in the interval 10 GeV - 13 TeV. We also investigate the role of the leading soft contribution, the low-energy cuttoff, and the energy dependence of the semihard form factor on these observables. We show that in all cases investigated the highly restrictive data on $rho$ parameter at $sqrt{s}=13$ TeV indicate that a crossing-odd component may play a crucial role in forward elastic scattering at the highest energies. In the Regge language an odd-under-crossing object is called Odderon.
We explore the theoretical observation that within the leading twist approximation, the nuclear effects of shadowing and antishadowing in non-perturbative nuclear parton distribution functions (nPDFs) at the input QCD evolution scale involve diffraction on nucleons of a nuclear target and originate from merging of two parton ladders belonging to two different nucleons, which are close in the rapidity space. It allows us to propose that for a given momentum fraction $x_P$ carried by the diffractive exchange, nuclear shadowing and antishadowing should compensate each other in the momentum sum rule for nPDFs locally on the interval $ln (x/x_P) le 1$. We realize this by constructing an explicit model of nuclear gluon antishadowing, which has a wide support in $x$, $10^{-4} < x < 0.2$, peaks at $x=0.05-0.1$ at the level of $approx 15$% for $^{208}$Pb at $Q_0^2=4$ GeV$^2$ and rather insignificantly depends on details of the model. We also studied the impact parameter $b$ dependence of antishadowing and found it to be slow.
Due to the rapid longitudinal expansion of the quark-gluon plasma created in heavy-ion collisions, large local-rest-frame momentum-space anisotropies are generated during the systems evolution. These momentum-space anisotropies complicate the modeling of heavy-quarkonium dynamics in the quark-gluon plasma due to the fact that the resulting inter-quark potentials are spatially anisotropic, requiring real-time solution of the 3D Schrodinger equation. Herein, we introduce a method for reducing anisotropic heavy-quark potentials to isotropic ones by introducing an effective screening mass that depends on the quantum numbers $l$ and $m$ of a given state. We demonstrate that, using the resulting effective Debye screening masses, one can solve a 1D Schrodinger equation and reproduce the full 3D results for the energies and binding energies of low-lying heavy-quarkonium bound states to relatively high accuracy. The resulting effective isotropic potential models could provide an efficient method for including momentum-anisotropy effects in open quantum system simulations of heavy-quarkonium dynamics in the quark-gluon plasma.
We present a detailed analysis of the kinetic and mass terms associated with the Landau gauge gluon propagator in the presence of dynamical quarks, and a comprehensive dynamical study of certain special kinematic limits of the three-gluon vertex. Our approach capitalizes on results from recent lattice simulations with (2+1) domain wall fermions, a novel nonlinear treatment of the gluon mass equation, and the nonperturbative reconstruction of the longitudinal three-gluon vertex from its fundamental Slavnov-Taylor identities. Particular emphasis is placed on the persistence of the suppression displayed by certain combinations of the vertex form factors at intermediate and low momenta, already known from numerous pure Yang-Mills studies. One of our central findings is that the inclusion of dynamical quarks moderates the intensity of this phenomenon only mildly, leaving the asymptotic low-momentum behavior unaltered, but displaces the characteristic zero crossing deeper into the infrared region. In addition, the effect of the three-gluon vertex is explored at the level of the renormalization-group invariant combination corresponding to the effective gauge coupling, whose size is considerably reduced with respect to its counterpart obtained from the ghost-gluon vertex. The main upshot of the above considerations is the further confirmation of the tightly interwoven dynamics between the two- and three-point sectors of QCD.
We discuss how the main features of the recent LHC data on elastic scattering can be described by a QCD-inspired formalism with a dynamical infrared mass scale. For this purpose new developments on a dynamical gluon mass approach are reported, with emphasis on a method to estimate uncertainty bounds in the predictions for the high-energy scattering observables. We investigate the effects due to the correlations among the fixed and free parameters involved and show that the band of predictions are consistent with the recent data from the TOTEM experiment, including the forward quantities and the differential cross section up to the dip position.
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